The present invention relates to a data transfer control device and an electronic instrument.
In recent years, a high-speed serial transfer interface such as a low voltage differential signaling (LVDS) interface has attracted attention as an interface aiming at reducing EMI noise or the like. In such a high-speed serial transfer, data is transferred by causing a transmitter circuit to transmit serialized data using differential signals and causing a receiver circuit to differentially amplify the differential signals (JP-A-2001-222249).
An ordinary portable telephone includes a first instrument section provided with buttons for inputting a telephone number or a character, a second instrument section provided with a main liquid crystal display (LCD), a sub LCD, and a camera (CCD), and a connection section (e.g. hinge) which connects the first and second instrument sections. The number of interconnects passing through the connection section can be reduced by transferring data between a first substrate provided in the first instrument section and a second substrate provided in the second instrument section by serial transfer using differential signals.
The format of camera data output from a camera (imaging device) such as a CCD or CMOS is various. Specific examples of such formats include YUV422, YUV420, RGB888, RGB565, RGB444, RAW6, RAW7, RAW8, RAW10, RAW12, and JPEG8. YUV422 data and YUV420 data are input as 8-bit data (data of which one data unit is eight bits). RGB888 data is input as 24-bit data, RGB565 data is input as 16-bit data, and RGB444 data is input as 12-bit data. RAW6 data, RAW7 data, RAW8 data, RAW10 data, and RAW12 data are respectively input as 6-bit data, 7-bit data, 8-bit data, 10-bit data, and 12-bit data, and JPEG8 data is input as 8-bit data. Therefore, it is desirable that such various formats be supported when packetizing camera data and serially transferring the packetized data from the second instrument section provided with the camera to the first instrument section provided with a host device.
However, if the number of bits of redundant data is increased when packetizing camera data in various formats, the amount of data transferred through the serial bus is increased. On the other hand, a problem such as an increase in the circuit scale occurs when dealing with various formats while setting the number of bits of redundant data at zero.